Research will be undertaken to determine the primary basis of toxicity of miconazole and imazalil to fungal cells. One specific point of emphasis will be to determine whether inhibited sterol biosynthesis of a direct action on the membrane is responsible for membrane deterioration. Other studies will be undertaken with fungi to compare effects of the fungicides miconazole and imazalil and of imidazoles, Benzothiadiaxazoles and other insecticide synergists on sterol metabolism with particular reference to inhibition specificity for mixed function oxidases of the sterol C-4 and C-14 demethylase types. In another aspect of these investigations, a study will be undertaken to determine site of action of tricyclazole in fungal polyketide metabolism and to relate this action to antipathogenic activity of the compound. The organisms to be used in this study are Verticillium dahliae and Pyricularia oryzae.